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eSATA capacity questions

Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by Rich, Nov 30, 2008.

  1. Rich

    Rich DBSTalk Club DBSTalk Club

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    Did you notice that Saxon is using the same RAID enclosure as you are? You are not alone.

    And your posts now look as if a rational person is writing them. Kudos!

    Rich
     
  2. Richierich

    Richierich Hall Of Fame

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    No, I didn't notice that Saxon was using the DS3RPRO but I will definitely talk to him about it to see what his setup experiences were. Can't wait for the 2 TB drives to come out as I will install those on Day 1 when they come out.

    Then we will see when I get close to being MAXED out if it is the RAID enclosure or the DB or something else.
     
  3. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    RAID-0 is a striped between the drives, so only 750 GBs of the 1 TB drive is being used, since it's paired with the 750 GB drive.
     
  4. TomCat

    TomCat Broadcast Engineer

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    Oh so true. Which raises the question, why is anyone even considering a RAID system for a DVR?

    Weaknees has a system that will mirror drives, but that is technically not RAID, in fact if you search their site for the word "RAID" it only picks up the word "afraid" half a dozen times.

    And actually, I question the value of their "mirror". AFAIK, the HR2x can only mount one drive at a time, which means that they must make the dual drives appear as if they were a single partition (which is indeed possibly similar to certain RAID configurations, but still not RAID). So what does that mean if something goes wrong with one of the two drives? Is there not the possibility that both drives would disappear?
     
  5. Rich

    Rich DBSTalk Club DBSTalk Club

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    So, naturally, I tried it and you're right. Never really had a reason to try this feature out. What else could "Keep Until I Delete" mean except keep until I delete? And yet there it is. These things even lie to us. Truly amazing.

    I guess I never used this feature on a TiVo either. Did the TiVo stop at five or ten and not add or delete any programs unless told to do so?

    I'll be really interested to see what happens when the first brave soul replaces the internal drive with a 2TB drive when they become available. I have a feeling that it will work perfectly. And if it does that will prove that the eSATA function itself is flawed, no?

    Rich
     
  6. Rich

    Rich DBSTalk Club DBSTalk Club

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    Huh. So with my two Cav 2TBs I have, they each have two 1TB drives and since both are the same size, they add to 2TB in RAID 0?

    And if you put a 500Gig and a 1TB in a RAID enclosure you would only get 1TB in total in RAID 0? And only 500G mirrored in RAID 1?

    Rich
     
  7. Richierich

    Richierich Hall Of Fame

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    As far as the HR2X DVR is concerned it only knows the existence of Drive 0, it doesn't even know Drive 1 exists. The RAID Enclosure then does the mirroring and the only problem would be if the data on Drive 0 is corrupted. If not at any time you can pull Drive 0 out of Bay 0 and put Drive 1 in Bay 0, then add a New Drive to Bay 1, tell the enclosure to Mirror Drive 0 to Drive 1 and you are back in business with all of your recordings.

    I personally don't believe the recordings are gone due to a reformat but just a perceived format and my procedure that I have hypothesized may indeed work but I personally have not had the opportunity to test it.

    If the External Drives were not reformatted then just going to the internal and back to the external should do the trick without having to go thru the mirroring process described above.
     
  8. Richierich

    Richierich Hall Of Fame

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    Yes, Rich that is right as it uses the smallest of the two drives to determine it's size. Normally, you would always use the same size drives in a RAID 1 Configuration ideally.
     
  9. Rich

    Rich DBSTalk Club DBSTalk Club

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    The 2TB Cavalrys were the biggest eSATAs I could get at a decent price and Cavalry tech support set them both up in what they called the "big" configuration. I guess that means RAID 0?

    When I called up weaknees.com the tech I spoke to called that a RAID enclosure. What would you call it? I ask this out of sheer ignorance, not to argue.

    I can't quite understand why what happened to me on the previous NR (one of my Cav 750s was wiped out and I tried the restore function twice with no luck) wouldn't happen on a RAID enclosure. I'm just an "end user" and am just learning about all this RAID stuff.

    Rich
     
  10. Rich

    Rich DBSTalk Club DBSTalk Club

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    So, essentially, Saxon wasted his money on that 1TB drive?

    Rich
     
  11. Richierich

    Richierich Hall Of Fame

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    Weaknees told me they were using a RAID Configuration they just don't call it that.

    Neither does TENBOX. They call their RAID 1, SAFE MODE which is indeed what it is.
     
  12. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    "My understanding" of RAID:
    RAID-1 is "simply" mirroring. No speed increase, but if a drive drops off line, the other is still there.
    RAID-0 is simply striping. Can have a speed increase as it dumps to the drive buffer as it is moving on to the next drive. If one drive drops off line, "you're hosed".
    RAID-5 has parity. it does have a speed increase [like RAID-0] but not as much due to the parity, but if a drive drops off line, will still function.
    There are the newer RAID-? that are a combination of striping and mirroring.
    "Back in the day" when a drive was a "whopping" 4 GB, this seemed to have been more important than today.
    Since the eSATA is "only for TV" [and not storing "the cure for cancer"] I tend to think a "JBOD" would work as the DVR only needs to see "the drives" as one drive. They can be striped, or simply "spanned" and function.
     
  13. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    "As I see it" mirroring only is useful for a drive dropping off line. "Garbage" in will be written to both drives [if they're both on line]. So if a reformat command is sent, both drives "get it" and "you're hosed".
    You would need to mirror [backup] one drive and then take the mirrored drive "off line" to not have it formated.
     
  14. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    "Or" is one step closer to the next 1 TB drive to get the full size to be used.
     
  15. TomCat

    TomCat Broadcast Engineer

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    I would certainly not call it a "RAID enclosure" unless it were running RAID. Technically, RAID is a software/firmware configuration of the hardware, not a physical enclosure. RAID implies the need for an enclosure that handles multiple drives, but such an enclosure does not imply that it is being used for RAID unless it also has dedicated support hardware such as a loop controller. I think RAID has to see the drives as a single volume, and I think the HR2x does as well since it can only seem to mount one at a time. But I don't really know.

    Now that I've raised the question (at least in my own mind) I would like to hear Weaknees explanation on all of this. I'd like to know if they just double record to a JBOD, and whether the drives appear as a single volume, and just exactly what benefit having their so-called "mirror" really buys you. I would have to assume that recordings are written to a single disk (once to one and once to another) rather than striped at block or sector level.

    It seems to me that double-recording yourself on multiple DVRs is a more reliable backup, although a bit more expensive and cumbersome. They are pretty communicative, so I will maybe drop them a email ASAP (unless someone else wants to--I've got a dying media server that is nagging me right now).
     
  16. Richierich

    Richierich Hall Of Fame

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    TC, the Mirror Function of a RAID Configuration in a RAID Enclosure is to have one drive backup the other in the event of drive failure. If both drives fail at the same time you are screwed but if just one drive fails then you take the Good Drive that is NOT failing and put it in Bay 0 (if it was not already in Bay 0) and then put the NEW Drive in Bay 1 and then tell Drive 0 to Mirror itself to Drive 1. Once that is done a green light comes on and you press the button to put it back in service and Power it up and you are back in business.
     
  17. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Considering that RAID 0 & 1 chips have been on motherboards for the past few years, "I think" the "RAID" enclosures are "just that", RAID-0 or RAID-1
     
  18. Richierich

    Richierich Hall Of Fame

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    Well, there are other RAID Configurations but those are the 2 most commons ones used.

    When you hear the Term nowadays, "RAID ENCLOSURE", particularly by retailers or manufacturers they are referring to an enclosure that houses at lease 2 hard drives using a RAID Controller so you can use the various RAID Settings depending upon your needs.
     
  19. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    These seem to be cheaper. The "other RAID" chips seem to be more costly.
     
  20. Richierich

    Richierich Hall Of Fame

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    And these two fit most uses. You either want more capacity or you want security with a backup in case of a drive failure which has happened to me three times on my 2 HR10-250s and I learned a very valuable lesson.

    Backup and recovery is extremely important to me as well as any serious user of a PC.
     

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